org.rhq.core.db

Class TypeMap

java.lang.Object

org.rhq.core.db.TypeMap

public class TypeMap
extends Object

This class performs XML parsing on content that defines database specific type mappings. This is how you define the type names that are valid for the different database vendors. A type map has one or more typemap nodes - a typemap defines a generic type (e.g. LONG, BOOLEAN) and a set of database specific types. You define a "generic" type name (the typemap element's type attribute) and you give a database vendor mapping that defines the database-specific type that is the most appropriate for that generic type. Here's an example for the generic type "LONG":

    <typemaps type="LONG">
       <typemap type="LONG">
          <map db="java"       type="BIGINT" />
          <map db="postgresql" type="BIGINT" />
          <map db="oracle"     type="NUMBER(19,0)" />
       </typemap>
    </typemaps>
 

The database name of "java" represents JDBC SQL types. The other database names are those that are returned by the different implementations of DatabaseType.getName().

Instances of this object are created via loadTypeMapsFromStream(InputStream) and loadKnownTypeMaps().

Method Summary

Methods

Modifier and Type	Method and Description
static String	getMappedType(Collection<TypeMap> typemaps, String generic_type, DatabaseType database) Given a collection of generic type maps, this returns the database specific type for the given generic type.
String	getMappedType(String generic_type, DatabaseType database) If this type map defines database types for the given generic type, this returns the type for the given database.
static Collection<TypeMap>	loadKnownTypeMaps() Loads in the known type maps.
static Collection<TypeMap>	loadTypeMapsFromStream(InputStream xml_stream) Given an input stream that contains an XML file of type maps, this will load in those type maps.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getMappedType

public String getMappedType(String generic_type,
                   DatabaseType database)

If this type map defines database types for the given generic type, this returns the type for the given database. If this type mapping does not define database specific types for the given generic type or it doesn't have a type defined for the given database, null is returned.

The database name (which is unique to a vendor/version) is first used to look up the type. If none is found, simply the vendor name is used to look up the type. This allows the XML to define a default type for all versions of a specific database vendor; but if a type needs to be different for a specific version of the vendor database, this allows for that.

If database is null, this means you are asking for a non-vendor-specific map type; in other words, the JDBC SQL type.

Parameters:

generic_type -

database -

Returns:

the database specific type that is to be used for the given generic type on the given database; will be null if the type is not found within this object.

toString

public String toString()

Overrides:

toString in class Object

See Also:

Object.toString()

getMappedType

public static String getMappedType(Collection<TypeMap> typemaps,
                   String generic_type,
                   DatabaseType database)

Given a collection of generic type maps, this returns the database specific type for the given generic type. If database is null, this means you are asking for a non-vendor-specific map type; in other words, the JDBC SQL type.

Parameters:

typemaps - collection of mappings for multiple generic types

generic_type - the generic type name whose corresponding database specific type is to be returned

database -

Returns:

returns the database specific type that maps to the given generic type; null is returned if there is no database specific mapping

loadKnownTypeMaps

public static Collection<TypeMap> loadKnownTypeMaps()

Loads in the known type maps. These type mappings are predefined in an XML file that ships with the code. The known types, once loaded, are cached in this object - calling this method afterwards will not re-parse the XML file, instead the cached type map collection will be returned.

Returns:

a collection of known type maps

Throws:

IllegalStateException - if the known XML file could not be loaded (should never occur) or was invalid

loadTypeMapsFromStream

public static Collection<TypeMap> loadTypeMapsFromStream(InputStream xml_stream)
                                                  throws Exception

Given an input stream that contains an XML file of type maps, this will load in those type maps.

Parameters:

xml_stream - the stream containing the XML mapping (must not be null)

Returns:

a collection of type maps as found in the given typemaps XML stream

Throws:

NullPointerException - if xml_stream is null

Exception - if the type maps data was invalid